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Front wheel motors

Posted: Sat May 22, 2010 1:27 pm
by DarrylH
I have been wondering how much difference there is with a front wheel motor in 26" and 700c wheels. I'm assuming that the kits in both sizes from the one manufacturer use the same motor so there will be some difference in gearing due to wheel diameter. I suspect that a 26" would be better for hilly terrain but a 700c would be better for speed. Does anyone have any direct knowledge of how much difference wheel diameter makes?

Re: Front wheel motors

Posted: Sat May 22, 2010 2:08 pm
by Joeblake
Can make quite a difference. On my electrikes I've got exactly the same motor (Heinzemann - 24v) and on one the driven (rear) wheel is 26" and on the other it is 16". On the 26" wheel the max speed (unassisted) on the flat is about 25 km/h, on the 16" wheel it is 17 km/h.

On the other hand the 16" wheel will just about climb a vertical wall, whereas the 26" really labours up the same hill.

Looking at the label on my motor it tells me it has a maximum rotational speed of 193 rpm, so even under no load at all it won't go past that limit.

As to the difference between front and rear wheel drive, I think they each have benefits and downsides. I think it's probably a matter of personal preference.

Joe

Re: Front wheel motors

Posted: Sat May 22, 2010 3:48 pm
by DarrylH
Thanks Joe, a friend has just about worn out her chain drive bike after 3 yrs and is looking at a front wheel conversion. My calculations for 26" v 700c showed about 25% gearing difference but it would be nice to know what that actually means on the road.
Of interest - taking into account only petrol and parking savings, she has paid for the bike and made about $1000 surplus towards the next one.

Darryl

Re: Front wheel motors

Posted: Sat May 22, 2010 3:57 pm
by Joeblake
One of the problems with putting the motor into the drive train rather than the hub is that it places extra stress on items like the chain and gear cluster, as your friend has found out, and if the motor is fairly powerful and the frame is not built to take this power, it can even distort the frame at the rear by applying excessive force.

I've never ridden a bike with a front wheel drive, and I'd be interested to see how this affects the steering.

Joe

Re: Front wheel motors

Posted: Sun May 23, 2010 4:21 pm
by hartleymartin
I'd like to see a kit where I can drop a new front wheel it, attach a small control box to the handlebars, a sensor to the bottom bracket and attach a battery pack and that is the whole of the "conversion". My bicycle would become a regular bicycle when I swap the original front wheel in and leave the battery pack at home. Nice, simple, modular. I don't want to have to make any changes more radical than that to my bicycle.

Re: Front wheel motors

Posted: Sun May 23, 2010 4:41 pm
by KenGS
hartleymartin wrote:I'd like to see a kit where I can drop a new front wheel it, attach a small control box to the handlebars, a sensor to the bottom bracket and attach a battery pack and that is the whole of the "conversion". My bicycle would become a regular bicycle when I swap the original front wheel in and leave the battery pack at home. Nice, simple, modular. I don't want to have to make any changes more radical than that to my bicycle.

Maybe a front wheel hub motor and mount the battery on a front rack?
I was also wondering if a single wheel trailer with a hub motor was legal and reasonably safe for the same reason.

Re: Front wheel motors

Posted: Sun May 23, 2010 4:53 pm
by Joeblake
hartleymartin wrote:I'd like to see a kit where I can drop a new front wheel it, attach a small control box to the handlebars, a sensor to the bottom bracket and attach a battery pack and that is the whole of the "conversion". My bicycle would become a regular bicycle when I swap the original front wheel in and leave the battery pack at home. Nice, simple, modular. I don't want to have to make any changes more radical than that to my bicycle.



This is what I did with my original trike. It started out with no motor, but Ian Sims at Greenspeed built a (rear) wheel for me which included the motor.

Image

I have been able to replace the motor wheel quite easily (but have chosen not to, mainly because I have to remove the solar panels, which wouldn't be a problem for you).

The batteries I put into a plastic tool box which is strapped to the carry rack.

Image

All the wiring can be disconnected from the control box, but rather than cutting the cable ties I left the wiring on the frame.

When I bought the motor, all the wiring was already done by the manufacturer.

Finally the throttle/switch just slips over the end of the handlebar to replace the handgrip.


Image

I think what you are after shouldn't be too much of a problem.

Joe

Re: Front wheel motors

Posted: Sun May 23, 2010 4:54 pm
by Joeblake
My new trike has got the battery carrier built into the frame, but other than that it would be easy to replace the wheel if I wished.

Image

Joe

Re: Front wheel motors

Posted: Sat Sep 04, 2010 5:55 pm
by glowwormbicycles
hartleymartin wrote:I'd like to see a kit where I can drop a new front wheel it, attach a small control box to the handlebars, a sensor to the bottom bracket and attach a battery pack and that is the whole of the "conversion". My bicycle would become a regular bicycle when I swap the original front wheel in and leave the battery pack at home. Nice, simple, modular. I don't want to have to make any changes more radical than that to my bicycle.


daahub.com is trying to keep it simple.

To keep it even simpler, dont worry about the bottom bracket sensor. But, dont lets get carried away - it will always take some time to swap one to the other. front hub motors usually have torque arms so that the axle doesn't spin inside your front drop outs - remember it's under load there.

I'd recommend a battery that slides under the pannier rack. they come out quickly and easily with a key and leave something useful - a pannier rack.